Jazz FAQ

Questions, Answered

What does it mean to "know the changes"?

It means knowing the bars: which chord is sounding in which bar of the form, and where the form comes back round. Melodies come and go, but a group can play a whole set together on nothing but agreement about the changes. See the changes engine for the forms this site declares bar by bar.

Knowing them in one key is not knowing them. A tune gets called in whichever key suits whoever is playing the melody, which is why every form on this site is declared as degrees and realized into all twelve rather than written out once.

What are rhythm changes?

A thirty-two-bar form in an A A B A order, built from two declared eight-bar sections: an A whose first half is a turnaround repeated, and a bridge that is nothing but four dominant sevenths walking round the cycle two bars each. See the rhythm changes page, where the chorus length is counted from the sections rather than asserted.

It matters because dozens of tunes share it. Learn the shape once and a large slice of the repertoire is a melody away.

Why would anyone substitute a chord that already works?

Because a substitution keeps the destination and changes the road. The tritone substitution swaps a dominant for another one a tritone away that shares the two notes carrying the pull, so the bass slides down a semitone instead of dropping a fifth. See the tritone page for the rule applied to every declared form.

The other rules on this site do the same kind of work: insert a chord, approach from the other side, or fill a step. None of them changes where the passage is going.

Which seat should I learn the changes from?

The piano seat teaches them fastest, because it is the only one that can state a whole chord and its substitute at the same time — see the piano seat's chord reference. The upright teaches them most thoroughly, because a walking line has to be right on every beat rather than once a bar.

Whichever you pick, the playing itself is taught on the sister site that owns the instrument. This site starts once you can make the sound.

Why Roman numerals and never numbers?

Roman numerals are how this idiom has written degrees for as long as it has written them down, and they carry quality in their own casing. Writing a progression as a run of digits is a different notation belonging to a different tradition and a different sister site, so you will not find it here.

Where is the list of standards?

There isn't one, deliberately. The tunes are somebody's copyright and their melodies are not this site's to publish. What is publishable — and more useful — is the shapes underneath them: see how long a standard is, measured from the declared forms.